1. Field of the Invention
The present invention relates to a lens-fitted photo film unit. More particularly, the present invention relates to a lens-fitted photo film unit incorporating an electronic flash device and being improved in view of convenience in charging operation of the flash device.
2. Description Related to the Prior Art
Lens-fitted photo film units are a single-use camera pre-loaded with photo film, and provided with simple mechanisms for effecting exposure, such as a shutter with a taking lens. A known photo film unit is disclosed in the commonly assigned U.S. Pat. No. 5,361,111 (corresponding to JP-A (Japanese Patent Laid-open Publication No.) 5-100302). Plural variants of photo film units are commercially available, including a flash built-in type "Fujicolor Quick Snap Flash" (trade name; manufactured by Fuji Photo Film Co., Ltd.). A flash device incorporated in the lens-fitted photo film unit includes a flash-emitting section having a discharge tube, and printed circuit board having a flash circuit. For flash photography, an operable portion disposed in front of the lens-fitted photo film unit is operated, to turn on a flash charge switch, so that a main capacitor of the printed circuit board is charged. After illumination at a lamp or an indicator of other structures is checked as a sign of finish of the charging, a shutter release button is depressed. Flash light is emitted at the same time as the release of the shutter.
The flash charge switch has a simplified structure in consistency with a low price of the lens-fitted photo film unit, and includes two contact points and a switch segment. The contact points are arranged on the printed circuit board, contacted on the switch segment, and short-circuited. In response the flash circuit is closed to start operation of the charging. Various examples of operable portions are known: a retainable sliding type in which a retaining mechanism is operated to retain the switch segment in contact with the contact points; and an unretained type in which the switch segment is contacted on the contact points only during depression of the operable portion with a user's finger. The unretained type has either of a pushbutton structure and a sliding structure. In general, the operable portion is formed integrally with a front cover of the lens-fitted photo film unit, and shiftable toward the switch segment with resiliency.
The known operable portion of the unretained type for the flash charging is inconvenient in use for taking plural successive exposures with flash light. The operable portion must be moved every time immediately after taking one exposure and before taking another with flash light, in course of taking plural successive exposures. The known operable portion of the retainable type in association with a retaining mechanism is inconvenient in use for taking only one exposure with flash light. Although the operable portion is moved for one time before taking plural successive exposures with flash light, the operable portion must be moved for two times before taking only one exposure: moved to the charging position and then back to the initial position without charging. If a user is not accustomed to using the lens-fitted photo film unit, it is likely that the lens-fitted photo film unit is left to stand with the operable portion set in the charging position for a long time, until all power of a battery is wasted, to disable the flash device from operating for the remaining ones of all photographable frames of the photo film.